Video processing method and apparatus for using palette mode

ABSTRACT

The present disclosure provides systems and methods for signaling and using a palette mode in video processing. According to certain disclosed embodiments, an exemplary video processing method includes: receiving a first palette entry for palette coding a target coding unit (CU); determining whether the target CU is part of a single-tree slice; determining whether the target CU is coded with separate luma and chroma trees; and in response to the target CU being determined to be part of a single-tree slice and be coded with separate luma and chroma trees, decoding a first component of the target CU based on the first palette entry, and decoding a second component of the target CU based on a default palette entry.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/062,135, filed on Oct. 2, 2020, which claims priority to U.S.Provisional Application No. 62/943,083, filed on Dec. 3, 2019, and U.S.Provisional Application No. 62/952,426, filed on Dec. 22, 2019, all ofwhich are incorporated herein by reference in their entireties.

TECHNICAL FIELD

The present disclosure generally relates to video processing, and moreparticularly, to methods and apparatuses for signaling and using apalette mode.

BACKGROUND

A video is a set of static pictures (or “frames”) capturing the visualinformation. To reduce the storage memory and the transmissionbandwidth, a video can be compressed before storage or transmission anddecompressed before display. The compression process is usually referredto as encoding and the decompression process is usually referred to asdecoding. There are various video coding formats which use standardizedvideo coding technologies, most commonly based on prediction, transform,quantization, entropy coding and in-loop filtering. The video codingstandards, such as the High Efficiency Video Coding (HEVC/H.265)standard, the Versatile Video Coding (VVC/H.266) standard AVS standards,specifying the specific video coding formats, are developed bystandardization organizations. With more and more advanced video codingtechnologies being adopted in the video standards, the coding efficiencyof the new video coding standards get higher and higher.

SUMMARY OF THE DISCLOSURE

The embodiments of the present disclosure provide a method and devicefor signaling and using a palette mode. In some exemplary embodiments, avideo processing method includes: receiving a first palette entry forpalette coding a target coding unit (CU); determining whether the targetCU is part of a single-tree slice; determining whether the target CU iscoded with separate luma and chroma trees; and in response to the targetCU being determined to be part of a single-tree slice and be coded withseparate luma and chroma trees, decoding a first component of the targetCU based on the first palette entry, and decoding a second component ofthe target CU based on a default palette entry.

In some embodiments, an exemplary video processing apparatus includes atleast one memory for storing instructions and at least one processor.The at least one processor is configured to execute the instructions tocause the apparatus to perform: receiving a first palette entry forpalette coding a target coding unit (CU); determining whether the targetCU is part of a single-tree slice; determining whether the target CU iscoded with separate luma and chroma trees; and in response to the targetCU being determined to be part of a single-tree slice and be coded withseparate luma and chroma trees, decoding a first component of the targetCU based on the first palette entry, and decoding a second component ofthe target CU based on a default palette entry.

In some embodiments, an exemplary non-transitory computer readablestorage medium stores a set of instructions. The set of instructions areexecutable by one or more processing devices to cause a video processingapparatus to perform: receiving a first palette entry for palette codinga target coding unit (CU); determining whether the target CU is part ofa single-tree slice; determining whether the target CU is coded withseparate luma and chroma trees; and in response to the target CU beingdetermined to be part of a single-tree slice and be coded with separateluma and chroma trees, decoding a first component of the target CU basedon the first palette entry, and decoding a second component of thetarget CU based on a default palette entry.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments and various aspects of the present disclosure areillustrated in the following detailed description and the accompanyingfigures. Various features shown in the figures are not drawn to scale.

FIG. 1 is a schematic diagram illustrating structures of an examplevideo sequence, according to some embodiments of the present disclosure.

FIG. 2 illustrates a schematic diagram of an exemplary encoder in ahybrid video coding system, according to some embodiments of the presentdisclosure.

FIG. 3 illustrates a schematic diagram of an exemplary decoder in ahybrid video coding system, according to some embodiments of the presentdisclosure.

FIG. 4 illustrates a block diagram of an exemplary apparatus forencoding or decoding a video, according to some embodiments of thepresent disclosure.

FIG. 5 illustrates a schematic diagram of an exemplary image block codedin palette mode, according to some embodiments of the presentdisclosure.

FIG. 6 illustrates a schematic diagram of an exemplary process forupdating palette predictor after encoding a coding unit, according tosome embodiments of the present disclosure.

FIG. 7 illustrates an exemplary Table 1 showing a part of sequenceparameter set (SPS) syntax table, according to some embodiments of thepresent disclosure.

FIG. 8 illustrates an exemplary Table 2 showing a part of coding unitsyntax table, according to some embodiments of the present disclosure.

FIG. 9 illustrates an exemplary Table 3 showing a part of palette codingsyntax table, according to some embodiments of the present disclosure.

FIG. 10 illustrates an exemplary decoding process for palette mode,according to some embodiments of the present disclosure.

FIG. 11 illustrates an exemplary Table 4 showing a part of palettecoding syntax table, according to some embodiments of the presentdisclosure.

FIG. 12 illustrates an exemplary palette coding semantics and decodingprocess for palette mode, according to some embodiments of the presentdisclosure.

FIG. 13 illustrates an exemplary Table 5 showing a part of the palettecoding syntax table, according to some embodiments of the presentdisclosure.

FIG. 14 illustrates an exemplary decoding process for palette mode,according to some embodiments of the present disclosure.

FIG. 15 illustrates an exemplary Table 6 showing a part of the codingunit syntax table, according to some embodiments of the presentdisclosure.

FIG. 16 illustrates an exemplary Table 7 showing a part of the palettecoding syntax table, according to some embodiments of the presentdisclosure.

FIG. 17 illustrates another exemplary palette coding semantics anddecoding process for palette mode, according to some embodiments of thepresent disclosure.

FIG. 18 illustrates a flowchart of an exemplary video processing method,according to some embodiments of the present disclosure.

FIG. 19 illustrates a flowchart of another exemplary video processingmethod, according to some embodiments of the present disclosure.

FIG. 20 illustrates a flowchart of another exemplary video processingmethod, according to some embodiments of the present disclosure.

FIG. 21 illustrates a flowchart of another exemplary video processingmethod, according to some embodiments of the present disclosure.

FIG. 22 illustrates a flowchart of another exemplary video processingmethod, according to some embodiments of the present disclosure.

FIG. 23 illustrates a flowchart of another exemplary video processingmethod, according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments, examplesof which are illustrated in the accompanying drawings. The followingdescription refers to the accompanying drawings in which the samenumbers in different drawings represent the same or similar elementsunless otherwise represented. The implementations set forth in thefollowing description of exemplary embodiments do not represent allimplementations consistent with the invention. Instead, they are merelyexamples of apparatuses and methods consistent with aspects related tothe invention as recited in the appended claims. Particular aspects ofthe present disclosure are described in greater detail below. The termsand definitions provided herein control, if in conflict with termsand/or definitions incorporated by reference.

The Joint Video Experts Team (JVET) of the ITU-T Video Coding ExpertGroup (ITU-T VCEG) and the ISO/IEC Moving Picture Expert Group (ISO/IECMPEG) is currently developing the Versatile Video Coding (VVC/H.266)standard. The VVC standard is aimed at doubling the compressionefficiency of its predecessor, the High Efficiency Video Coding(HEVC/H.265) standard. In other words, VVC's goal is to achieve the samesubjective quality as HEVC/H.265 using half the bandwidth.

In order to achieve the same subjective quality as HEVC/H.265 using halfthe bandwidth, the JVET has been developing technologies beyond HEVCusing the joint exploration model (JEM) reference software. As codingtechnologies were incorporated into the JEM, the JEM achievedsubstantially higher coding performance than HEVC. The VCEG and MPEGhave formally started the development of next generation videocompression standard beyond HEVC.

The VVC standard has been developed recent, and continues to includemore coding technologies that provide better compression performance.VVC is based on the same hybrid video coding system that has been usedin modern video compression standards such as HEVC, H.264/AVC, MPEG2,H.263, etc.

A video is a set of static pictures (or “frames”) arranged in a temporalsequence to store visual information. A video capture device (e.g., acamera) can be used to capture and store those pictures in a temporalsequence, and a video playback device (e.g., a television, a computer, asmartphone, a tablet computer, a video player, or any end-user terminalwith a function of display) can be used to display such pictures in thetemporal sequence. Also, in some applications, a video capturing devicecan transmit the captured video to the video playback device (e.g., acomputer with a monitor) in real-time, such as for surveillance,conferencing, or live broadcasting.

For reducing the storage space and the transmission bandwidth needed bysuch applications, the video can be compressed before storage andtransmission and decompressed before the display. The compression anddecompression can be implemented by software executed by a processor(e.g., a processor of a generic computer) or specialized hardware. Themodule for compression is generally referred to as an “encoder,” and themodule for decompression is generally referred to as a “decoder.” Theencoder and decoder can be collectively referred to as a “codec.” Theencoder and decoder can be implemented as any of a variety of suitablehardware, software, or a combination thereof. For example, the hardwareimplementation of the encoder and decoder can include circuitry, such asone or more microprocessors, digital signal processors (DSPs),application-specific integrated circuits (ASICs), field-programmablegate arrays (FPGAs), discrete logic, or any combinations thereof. Thesoftware implementation of the encoder and decoder can include programcodes, computer-executable instructions, firmware, or any suitablecomputer-implemented algorithm or process fixed in a computer-readablemedium. Video compression and decompression can be implemented byvarious algorithms or standards, such as MPEG-1, MPEG-2, MPEG-4, H.26xseries, or the like. In some applications, the codec can decompress thevideo from a first coding standard and re-compress the decompressedvideo using a second coding standard, in which case the codec can bereferred to as a “transcoder.”

The video encoding process can identify and keep useful information thatcan be used to reconstruct a picture and disregard unimportantinformation for the reconstruction. If the disregarded, unimportantinformation cannot be fully reconstructed, such an encoding process canbe referred to as “lossy.” Otherwise, it can be referred to as“lossless.” Most encoding processes are lossy, which is a tradeoff toreduce the needed storage space and the transmission bandwidth.

The useful information of a picture being encoded (referred to as a“current picture”) include changes with respect to a reference picture(e.g., a picture previously encoded and reconstructed). Such changes caninclude position changes, luminosity changes, or color changes of thepixels, among which the position changes are mostly concerned. Positionchanges of a group of pixels that represent an object can reflect themotion of the object between the reference picture and the currentpicture.

A picture coded without referencing another picture (i.e., it is its ownreference picture) is referred to as an “I-picture.” A picture codedusing a previous picture as a reference picture is referred to as a“P-picture.” A picture coded using both a previous picture and a futurepicture as reference pictures (i.e., the reference is “bi-directional”)is referred to as a “B-picture.”

FIG. 1 illustrates structures of an example video sequence 100,according to some embodiments of the present disclosure. Video sequence100 can be a live video or a video having been captured and archived.Video 100 can be a real-life video, a computer-generated video (e.g.,computer game video), or a combination thereof (e.g., a real-life videowith augmented-reality effects). Video sequence 100 can be inputted froma video capture device (e.g., a camera), a video archive (e.g., a videofile stored in a storage device) containing previously captured video,or a video feed interface (e.g., a video broadcast transceiver) toreceive video from a video content provider.

As shown in FIG. 1 , video sequence 100 can include a series of picturesarranged temporally along a timeline, including pictures 102, 104, 106,and 108. Pictures 102-106 are continuous, and there are more picturesbetween pictures 106 and 108. In FIG. 1 , picture 102 is an I-picture,the reference picture of which is picture 102 itself. Picture 104 is aP-picture, the reference picture of which is picture 102, as indicatedby the arrow. Picture 106 is a B-picture, the reference pictures ofwhich are pictures 104 and 108, as indicated by the arrows. In someembodiments, the reference picture of a picture (e.g., picture 104) canbe not immediately preceding or following the picture. For example, thereference picture of picture 104 can be a picture preceding picture 102.It should be noted that the reference pictures of pictures 102-106 areonly examples, and the present disclosure does not limit embodiments ofthe reference pictures as the examples shown in FIG. 1 .

Typically, video codecs do not encode or decode an entire picture at onetime due to the computing complexity of such tasks. Rather, they cansplit the picture into basic segments, and encode or decode the picturesegment by segment. Such basic segments are referred to as basicprocessing units (“BPUs”) in the present disclosure. For example,structure 110 in FIG. 1 shows an example structure of a picture of videosequence 100 (e.g., any of pictures 102-108). In structure 110, apicture is divided into 4×4 basic processing units, the boundaries ofwhich are shown as dash lines. In some embodiments, the basic processingunits can be referred to as “macroblocks” in some video coding standards(e.g., MPEG family, H.261, H.263, or H.264/AVC), or as “coding treeunits” (“CTUs”) in some other video coding standards (e.g., H.265/HEVCor H.266/VVC). The basic processing units can have variable sizes in apicture, such as 128×128, 64×64, 32×32, 16×16, 4×8, 16×32, or anyarbitrary shape and size of pixels. The sizes and shapes of the basicprocessing units can be selected for a picture based on the balance ofcoding efficiency and levels of details to be kept in the basicprocessing unit.

The basic processing units can be logical units, which can include agroup of different types of video data stored in a computer memory(e.g., in a video frame buffer). For example, a basic processing unit ofa color picture can include a luma component (Y) representing achromaticbrightness information, one or more chroma components (e.g., Cb and Cr)representing color information, and associated syntax elements, in whichthe luma and chroma components can have the same size of the basicprocessing unit. The luma and chroma components can be referred to as“coding tree blocks” (“CTBs”) in some video coding standards (e.g.,H.265/HEVC or H.266/VVC). Any operation performed to a basic processingunit can be repeatedly performed to each of its luma and chromacomponents.

Video coding has multiple stages of operations, examples of which areshown in FIG. 2 and FIG. 3 . For each stage, the size of the basicprocessing units can still be too large for processing, and thus can befurther divided into segments referred to as “basic processingsub-units” in the present disclosure. In some embodiments, the basicprocessing sub-units can be referred to as “blocks” in some video codingstandards (e.g., MPEG family, H.261, H.263, or H.264/AVC), or as “codingunits” (“CUs”) in some other video coding standards (e.g., H.265/HEVC orH.266/VVC). A basic processing sub-unit can have the same or smallersize than the basic processing unit. Similar to the basic processingunits, basic processing sub-units are also logical units, which caninclude a group of different types of video data (e.g., Y, Cb, Cr, andassociated syntax elements) stored in a computer memory (e.g., in avideo frame buffer). Any operation performed to a basic processingsub-unit can be repeatedly performed to each of its luma and chromacomponents. It should be noted that such division can be performed tofurther levels depending on processing needs. It should also be notedthat different stages can divide the basic processing units usingdifferent schemes.

For example, at a mode decision stage (an example of which is shown inFIG. 2 ), the encoder can decide what prediction mode (e.g.,intra-picture prediction or inter-picture prediction) to use for a basicprocessing unit, which can be too large to make such a decision. Theencoder can split the basic processing unit into multiple basicprocessing sub-units (e.g., CUs as in H.265/HEVC or H.266/VVC), anddecide a prediction type for each individual basic processing sub-unit.

For another example, at a prediction stage (an example of which is shownin FIG. 2 ), the encoder can perform prediction operation at the levelof basic processing sub-units (e.g., CUs). However, in some cases, abasic processing sub-unit can still be too large to process. The encodercan further split the basic processing sub-unit into smaller segments(e.g., referred to as “prediction blocks” or “PBs” in H.265/HEVC orH.266/VVC), at the level of which the prediction operation can beperformed.

For another example, at a transform stage (an example of which is shownin FIG. 2 ), the encoder can perform a transform operation for residualbasic processing sub-units (e.g., CUs). However, in some cases, a basicprocessing sub-unit can still be too large to process. The encoder canfurther split the basic processing sub-unit into smaller segments (e.g.,referred to as “transform blocks” or “TBs” in H.265/HEVC or H.266/VVC),at the level of which the transform operation can be performed. Itshould be noted that the division schemes of the same basic processingsub-unit can be different at the prediction stage and the transformstage. For example, in H.265/HEVC or H.266/VVC, the prediction blocksand transform blocks of the same CU can have different sizes andnumbers.

In structure 110 of FIG. 1 , basic processing unit 112 is furtherdivided into 3×3 basic processing sub-units, the boundaries of which areshown as dotted lines. Different basic processing units of the samepicture can be divided into basic processing sub-units in differentschemes.

In some implementations, to provide the capability of parallelprocessing and error resilience to video encoding and decoding, apicture can be divided into regions for processing, such that, for aregion of the picture, the encoding or decoding process can depend on noinformation from any other region of the picture. In other words, eachregion of the picture can be processed independently. By doing so, thecodec can process different regions of a picture in parallel, thusincreasing the coding efficiency. Also, when data of a region iscorrupted in the processing or lost in network transmission, the codeccan correctly encode or decode other regions of the same picture withoutreliance on the corrupted or lost data, thus providing the capability oferror resilience. In some video coding standards, a picture can bedivided into different types of regions. For example, H.265/HEVC andH.266/VVC provide two types of regions: “slices” and “tiles.” It shouldalso be noted that different pictures of video sequence 100 can havedifferent partition schemes for dividing a picture into regions.

For example, in FIG. 1 , structure 110 is divided into three regions114, 116, and 118, the boundaries of which are shown as solid linesinside structure 110. Region 114 includes four basic processing units.Each of regions 116 and 118 includes six basic processing units. Itshould be noted that the basic processing units, basic processingsub-units, and regions of structure 110 in FIG. 1 are only examples, andthe present disclosure does not limit embodiments thereof.

FIG. 2 illustrates a schematic diagram of an exemplary encoder 200 in ahybrid video coding system, according to some embodiments of the presentdisclosure. Video encoder 200 may perform intra- or inter-coding ofblocks within video frames, including video blocks, or partitions orsub-partitions of video blocks. Intra-coding may rely on spatialprediction to reduce or remove spatial redundancy in video within agiven video frame. Inter-coding may rely on temporal prediction toreduce or remove temporal redundancy in video within adjacent frames ofa video sequence. Intra modes may refer to a number of spatial basedcompression modes. Inter modes (such as uni-prediction or bi-prediction)may refer to a number of temporal-based compression modes.

Referring to FIG. 2 , input video signal 202 may be processed block byblock. For example, the video block unit may be a 16×16 pixel block(e.g., a macroblock (MB)). The size of the video block units may vary,depending on the coding techniques used, and the required accuracy andefficiency. In HEVC, extended block sizes (e.g., a coding tree unit(CTU)) may be used to compress video signals of resolution, e.g., 1080pand beyond. In HEVC, a CTU may include up to 64×64 luma samplescorresponding chroma samples, and associated syntax elements. In VVC,the size of a CTU may be further increased to include 128×128 lumasamples, corresponding chroma samples, and associated syntax elements. ACTU can be further divided into coding units (CUs) using, for example,quad-tree, binary tree, or ternary tree. A CU may be further partitionedinto prediction units (PUs), for which separate prediction methods maybe applied. Each input video block may be processed by using spatialprediction unit 260 or temporal prediction unit 262.

Spatial prediction unit 260 performs spatial prediction (e.g., intraprediction) to the current block/CU using information on the samepicture/slice containing the current block. Spatial prediction may usepixels from the already coded neighboring blocks in the same videopicture frame/slice to predict the current video block. Spatialprediction may reduce spatial redundancy inherent in the video signal.

Temporal prediction unit 262 performs temporal prediction (e.g., interprediction) to the current block using information frompicture(s)/slice(s) different from the picture/slice containing thecurrent block. Temporal prediction for a video block may be signaled byone or more motion vectors. In unit-directional temporal prediction,only one motion vector indicating one reference picture is used togenerate the prediction signal for the current block. On the other hand,in bi-directional temporal prediction, two motion vectors, eachindicating a respective reference picture, can be used to generate theprediction signal for the current block. The motion vectors may indicatethe amount and the direction of motion between the current block and oneor more associated block(s) in the reference frames. If multiplereference pictures are supported, one or more reference picture indicesmay be sent for a video block. The one or more reference indices may beused to identify from which reference picture(s) in the referencepicture store or decoded picture buffer (DPB) 264, the temporalprediction signal may come.

Mode decision and encoder control unit 280 in the encoder may choose theprediction mode, for example, based on rate-distortion optimization.Based on the determined prediction mode, the prediction block can beobtained. The prediction block may be subtracted from the current videoblock at adder 216. The prediction residual may be transformed bytransformation unit 204 and quantized by quantization unit 206. Thequantized residual coefficients may be inverse quantized at inversequantization unit 210 and inverse transformed at inverse transform unit212 to form the reconstructed residual. The reconstructed residual maybe added to the prediction block at adder 226 to form the reconstructedvideo block. The reconstructed video block before loop-filtering may beused to provide reference samples for intra prediction.

The reconstructed video block may go through loop filtering at loopfilter 266. For example, loop filtering such as deblocking filter,sample adaptive offset (SAO), and adaptive loop filter (ALF) may beapplied. The reconstructed block after loop filtering may be stored inreference picture store 264 and can be used to provide inter predictionreference samples for coding other video blocks. To form the outputvideo bitstream 220, coding mode (e.g., inter or intra), prediction modeinformation, motion information, and quantized residual coefficients maybe sent to the entropy coding unit 208 to further reduce the bit rate,before the data are compressed and packed to form bitstream 220.

FIG. 3 illustrates a schematic diagram of an exemplary decoder 300 in ahybrid video coding system, according to some embodiments of the presentdisclosure. Referring to FIG. 3 , a video bitstream 302 may be unpackedor entropy decoded at entropy decoding unit 308. The coding modeinformation can be used to determine whether the spatial prediction unit360 or the temporal prediction unit 362 is to be selected. Theprediction mode information can be sent to the corresponding predictionunit to generate the prediction block. For example, motion compensatedprediction may be applied by the temporal prediction unit 362 to formthe temporal prediction block.

The residual coefficients may be sent to inverse quantization unit 310and inverse transform unit 312 to obtain the reconstructed residual. Theprediction block and the reconstructed residual can be added together at326 to form the reconstructed block before loop filtering. Thereconstructed block may then go through loop filtering at loop filer366. For example, loop filtering such as deblocking filter, SAO, and ALFmay be applied. The reconstructed block after loop filtering can then bestored in reference picture store 364. The reconstructed data in thereference picture store 364 may be used to obtain decoded video 320, orused to predict future video blocks. Decoded video 320 may be displayedon a display device, such as a TV, a PC, a smartphone, or a tablet to beviewed by the end-users.

FIG. 4 is a block diagram of an exemplary apparatus 400 for encoding ordecoding a video, according to some embodiments of the presentdisclosure. As shown in FIG. 4 , apparatus 400 can include processor402. When processor 402 executes instructions described herein,apparatus 400 can become a specialized machine for video encoding ordecoding. Processor 402 can be any type of circuitry capable ofmanipulating or processing information. For example, processor 402 caninclude any combination of any number of a central processing unit (or“CPU”), a graphics processing unit (or “GPU”), a neural processing unit(“NPU”), a microcontroller unit (“MCU”), an optical processor, aprogrammable logic controller, a microcontroller, a microprocessor, adigital signal processor, an intellectual property (IP) core, aProgrammable Logic Array (PLA), a Programmable Array Logic (PAL), aGeneric Array Logic (GAL), a Complex Programmable Logic Device (CPLD), aField-Programmable Gate Array (FPGA), a System On Chip (SoC), anApplication-Specific Integrated Circuit (ASIC), or the like. In someembodiments, processor 402 can also be a set of processors grouped as asingle logical component. For example, as shown in FIG. 4 , processor402 can include multiple processors, including processor 402 a,processor 402 b, and processor 402 n.

Apparatus 400 can also include memory 404 configured to store data(e.g., a set of instructions, computer codes, intermediate data, or thelike). For example, as shown in FIG. 4 , the stored data can includeprogram instructions (e.g., program instructions for implementing thestages in FIG. 2 or FIG. 3 ) and data for processing. Processor 402 canaccess the program instructions and data for processing (e.g., via bus410), and execute the program instructions to perform an operation ormanipulation on the data for processing. Memory 404 can include ahigh-speed random-access storage device or a non-volatile storagedevice. In some embodiments, memory 404 can include any combination ofany number of a random-access memory (RAM), a read-only memory (ROM), anoptical disc, a magnetic disk, a hard drive, a solid-state drive, aflash drive, a security digital (SD) card, a memory stick, a compactflash (CF) card, or the like. Memory 404 can also be a group of memories(not shown in FIG. 4 ) grouped as a single logical component.

Bus 410 can be a communication device that transfers data betweencomponents inside apparatus 400, such as an internal bus (e.g., aCPU-memory bus), an external bus (e.g., a universal serial bus port, aperipheral component interconnect express port), or the like.

For ease of explanation without causing ambiguity, processor 402 andother data processing circuits are collectively referred to as a “dataprocessing circuit” in the present disclosure. The data processingcircuit can be implemented entirely as hardware, or as a combination ofsoftware, hardware, or firmware. In addition, the data processingcircuit can be a single independent module or can be combined entirelyor partially into any other component of apparatus 400.

Apparatus 400 can further include network interface 406 to provide wiredor wireless communication with a network (e.g., the Internet, anintranet, a local area network, a mobile communications network, or thelike). In some embodiments, network interface 406 can include anycombination of any number of a network interface controller (NIC), aradio frequency (RF) module, a transponder, a transceiver, a modem, arouter, a gateway, a wired network adapter, a wireless network adapter,a Bluetooth adapter, an infrared adapter, a near-field communication(“NFC”) adapter, a cellular network chip, or the like.

In some embodiments, optionally, apparatus 400 can further includeperipheral interface 408 to provide a connection to one or moreperipheral devices. As shown in FIG. 4 , the peripheral device caninclude, but is not limited to, a cursor control device (e.g., a mouse,a touchpad, or a touchscreen), a keyboard, a display (e.g., acathode-ray tube display, a liquid crystal display, or a light-emittingdiode display), a video input device (e.g., a camera or an inputinterface coupled to a video archive), or the like.

It should be noted that video codecs can be implemented as anycombination of any software or hardware modules in apparatus 400. Forexample, some or all stages of encoder 200 of FIG. 2 or decoder 300 ofFIG. 3 can be implemented as one or more software modules of apparatus400, such as program instructions that can be loaded into memory 404.For another example, some or all stages of encoder 200 of FIG. 2 ordecoder 300 of FIG. 3 can be implemented as one or more hardware modulesof apparatus 400, such as a specialized data processing circuit (e.g.,an FPGA, an ASIC, an NPU, or the like).

In the quantization and inverse quantization functional blocks (e.g.,quantization unit 206 and inverse quantization unit 210 of FIG. 2 ,inverse quantization unit 310 of FIG. 3 ), a quantization parameter (QP)is used to determine the amount of quantization (and inversequantization) applied to the prediction residuals. Initial QP valuesused for coding of a picture or slice may be signaled at the high level,for example, using syntax element init_qp_minus26 in the PictureParameter Set (PPS) and using syntax element slice_qp_delta in the sliceheader. Further, the QP values may be adapted at the local level foreach CU using delta QP values sent at the granularity of quantizationgroups.

In VVC (e.g., VVC draft 7), palette mode is used in 4:4:4 color format.When the palette mode is enabled, a flag is transmitted at the CU levelif the CU size is smaller than or equal to 64×64 indicating whether thepalette mode is used.

FIG. 5 illustrates a schematic diagram of an exemplary image block 500coded in palette mode, according to some embodiments of the presentdisclosure. As shown in FIG. 5 , if the palette mode is utilized to codea current CU, the sample values in each position in the CU arerepresented by a small set of representative color values. The set isreferred to as a palette (e.g., palette 510). For sample positions(e.g., positions 501, 502, or 503) with values close to the palettecolors, the corresponding palette indices (e.g., index 0, index 1, index2, or index 3) are signaled. According to some disclosed embodiments, acolor value that is outside the palette can be specified by signaling anescape index (or escape color index). Then, for all positions (e.g.,position 504) in the CU that use the escape color index (e.g., index 4),the (quantized) color component values are signaled for each of thesepositions.

For coding the palette, a palette predictor is maintained. The predictoris initialized to 0 (e.g., empty) at the beginning of each slice fornon-wavefront case and at the beginning of each CTU row for wavefrontcase. FIG. 6 illustrates a schematic diagram of an exemplary process 600for updating palette predictor after encoding a coding unit, accordingto some embodiments of the present disclosure. As shown in FIG. 6 , foreach entry in the palette predictor, a reuse flag is signaled toindicate whether it will be included in the current palette of thecurrent CU. The reuse flags are sent using run-length coding of zeros,after which the number of new palette entries and the component valuesfor the new palette entries are signaled. After encoding the palettecoded CU, the palette predictor is updated using the current palette,and entries from the previous palette predictor that are not reused inthe current palette are added at the end of the new palette predictoruntil the maximum size allowed is reached.

In some embodiments, an escape flag is signaled for each CU to indicateif escape symbols are present in the current CU. If escape symbols arepresent, the palette table is augmented by one and the last index (e.g.,index 4 as shown in FIG. 5 ) is assigned to be the escape symbol.

Referring back to FIG. 5 , palette indices (e.g., index 0, index 1,index 2, index 3, and index 4) of samples in a CU form a palette indexmap. The index map is coded using horizontal or vertical traverse scans.The scan order is explicitly signaled in the bitstream using syntaxelement palette_transpose_flag. The palette index map is coded using theindex-run mode or the index-copy mode.

In some embodiments, the palette mode is allowed only for 4:4:4 colorformat. However, a large amount of video content may be coded with othercolor formats, e.g., the 4:2:0 chroma sub-sampling format. The presentdisclosure provides methods to extend the palette mode to other chromaformats such as monochrome, 4:2:0, 4:2:2, etc.

Moreover, for slices with dual luma/chroma tree, the palette is appliedon luma (Y component) and chroma (Cb and Cr components) separately. Forslices of single tree, the palette is applied on Y, Cb, Cr componentsjointly (e.g., each entry in the palette contains Y, Cb, Cr values).However, in VVC, for 4:2:0 and 4:2:2 color format, a coding unit (CU) ofa single-tree slice can have separate luma and chroma trees due to therestriction on the allowable smallest chroma coding block sizes. Hence,the joint palette cannot be applied to the dual-tree CU because luma andchroma of the dual-tree CU are processed separately (although the CUbelongs to a single-tree slice). Thus, in some embodiments of thepresent disclosure, while extending the palette mode to other chromaformats such as 4:2:0 and 4:2:2, the possibilities of a single-treeslice with a local dual-tree structure (e.g., single tree at slice levelwhile dual tree at CU level) can be addressed.

Some embodiments of the present disclosure provide methods and apparatusfor applying the palette mode to color formats other than the 4:4:4color format (or non 4:4:4 color format), and to single-tree slice withlocal dual-tree structures.

Some embodiments of the present disclosure can allow the palette modefor all chroma formats, such as monochrome, 4:2:0, 4:2:2, 4:4:4, etc.FIG. 7 illustrates an exemplary Table 1 showing a part of SPS syntaxtable, according to some embodiments of the present disclosure. As shownin Table 1, the syntax elements that are stricken through in box 701 areproposed to be deleted from the current VVC draft 7, and the syntaxelements that are italicized in box 702 are proposed to be added to thecurrent VVC draft 7. The SPS flag sps_palette_enabled_flag can besignaled regardless of the value of syntax element chroma_format_idc.

As explained above, in the current video coding standard (for example,VVC draft 7), for slices with single tree, the palette mode is appliedon Y, Cb, Cr components jointly. The P and B slices are always coded assingle-tree slices. The tree structure of I slices are signaled throughSPS syntax, e.g., syntax element qtbtt_dual_tree_intra_flag. Syntaxelement qtbtt_dual_tree_intra_flag equal to 1 specifies that for Islices, two separate coding_tree syntax structures for luma and chromaare used. Syntax element qtbtt_dual_tree_intra_flag equal to 0 specifiesthat separate coding_tree syntax structure is not used for I slices.

A coding unit of a single-tree slice can have separate luma and chromatrees, because in case of a non-inter smallest chroma intra predictionunit (SCIPU), chroma is not allowed to be further split, but luma isallowed to be further split. In single-tree coding, an SCIPU is definedas a coding tree node whose chroma block size is larger than or equal to16 chroma samples and has at least one child luma block smaller than 64luma samples. Hence, the joint palette cannot be applied to a dual-treeCU because luma and chroma of the dual-tree CU are processed separately(although the dual-tree CU belong to a single-tree slice). This presentsan issue for applying the palette mode to a single-tree slice withdual-tree CUs. The present disclosure provides some embodiments toaddress this issue.

According to some embodiments, the palette mode is not allowed for a CUif the CU contains local dual trees. Therefore, the palette mode is notallowed for a CU if both of the following conditions are satisfied: (1)the CU is coded with separate trees, and (2) the CU belongs to a slicewith single tree. FIG. 8 illustrates an exemplary Table 2 showing a partof the coding unit syntax table, according to some embodiments of thepresent disclosure. The coding unit syntax table of Table 2 can disallowthe palette mode for a CU. As shown in Table 2, the syntax changesconsistent with the present embodiments are italicized in box 801. Basedon the coding unit syntax table of Table 2, the palette mode is notallowed if the following two conditions are satisfied:

(treeType ! = SINGLE_TREE) && (slice_type ! = I | |qtbtt_dual_tree_intra_flag == 0)

According to some embodiments, to improve the coding efficiency ofpalette mode, the palette mode is applied to a CU containing local dualtrees. For a local dual tree block, the reuse flags (e.g. syntax elementpalette_predictor_run) are signaled without new palette entry (e.g.syntax element new_palette_entries[cldx][i]) being added. Since thelocal dual-tree block may only contain luma (or chroma) component, thechroma (or luma) value for the new palette entry may be empty. Thus,sending new palette entry for the local dual-tree blocks is restricted.FIG. 9 illustrates an exemplary Table 3 showing a part of the palettecoding syntax table, according to some embodiments of the presentdisclosure. The palette coding syntax table of Table 3 can apply thepalette mode to a CU containing local dual trees. As shown in Table 3,the syntax changes consistent with the present embodiments areitalicized in boxes 901-904.

Moreover, for non 4:4:4 color format, there are pixels only containingluma component. Therefore, in some embodiments, only luma values aresignaled for these pixels when they are coded using escape mode (seesyntax in Table 3 of FIG. 9 that are both bold and shaded in box 903).

FIG. 10 illustrates an exemplary decoding process for palette mode,according to some embodiments of the present disclosure. The decodingprocess includes the section 8.4.5.3 in VVC draft 7. Decoding processcan contains two processes, one for pixel reconstruction and the otherfor palette predictor update.

As shown in FIG. 10 , decoding process can be similar to section 8.4.5.3in VVC draft 7. Decoding process can include some syntax changes thatare italicized in boxes 1001-1003. When updating the palette predictorusing the current palette, entries for the current palette are put inthe front of the new palette predictor. Then, entries from the previouspalette predictor that are not reused in the current palette are addedat the end of the new palette predictor. For the local dual-tree blocks,each palette entry contains both luma and chroma components. Therefore,all three components are involved in the process of palette predictorupdate. It is a requirement of bitstream conformance that the value ofPredictorPaletteSize[startComp] is in the range of 0 to 63, inclusive.

According to some embodiments, the palette mode can be applied to alocal dual-tree block in the same way as the palette mode applied to asingle-tree block. Because the local dual-tree block may only containluma (or chroma) component, the value of luma (or chroma) component issignaled and a default value can be set to the chroma (or luma)component for the new palette entry. As an example, the default valuemay be related to the video sequence's bit depth. As another example,the default value may be zero.

Moreover, for non 4:4:4 color format, only luma values are signaled forpixels only containing luma components when they are coded using escapemode. FIG. 11 illustrates an exemplary Table 4 showing a part of thepalette coding syntax table, according to some embodiments of thepresent disclosure. The palette coding syntax table of Table 4 can applythe palette mode to a CU containing local dual trees. As shown in Table4, the syntax changes consistent with the present embodiments areitalicized in box 1101 and box 1102.

In some embodiments of the present disclosure, the syntax parsing forthe local dual tree can be aligned with that for the single tree.Moreover, the coding efficiency for palette mode can be improved becauseless bits are signaled.

FIG. 12 illustrates an exemplary palette coding semantics and decodingprocess for palette mode, according to some embodiments of the presentdisclosure. As shown in FIG. 12 , the proposed syntax changes to thesection 7.4.12.6 and the section 8.4.5.3 in VVC draft 7 are italicizedin box 1201-1205. For the local dual-tree blocks, when performing thepalette predictor update, a default value is first filled in the currentpalette (see semantics in bold in FIG. 12 ). Then, all three componentsare involved in the process of palette predictor update. It is arequirement of bitstream conformance that the value ofPredictorPaletteSize[startComp] is in the range of 0 to 63, inclusive.

According to some embodiments, the palette mode can be applied to alocal dual tree block in the same way as the palette mode is applied toa single-tree block, which is similar to the embodiments shown in Table4 of FIG. 11 . However, in some embodiments, the palette for the localdual-tree block is not used to update the palette predictor. Therefore,the decoding process can be simplified because the reordering process inpalette predictor is skipped.

Moreover, for non 4:4:4 color format, only luma values are signaled forpixels only containing luma components when they are coded using escapemode. FIG. 13 illustrates an exemplary Table 5 showing a part of thepalette coding syntax table, according to some embodiments of thepresent disclosure. The palette coding syntax table of Table 5 can applythe palette mode to a CU containing local dual trees. As shown in Table5, the syntax changes consistent with the present embodiments areitalicized in box 1301 and box 1302.

FIG. 14 illustrates an exemplary decoding process for palette mode,according to some embodiments of the present disclosure. As shown inFIG. 14 , the proposed syntax change to the section 8.4.5.3 in VVC draft7 are italicized in box 1401 and box 1402. For the local dual-treeblocks, the palette predictor is not updated. It is a requirement ofbitstream conformance that the value of PredictorPaletteSize[startComp]is in the range of 0 to 63, inclusive.

According to some embodiments, the palette mode can be applied to alocal dual-tree luma block in the same way as the palette mode appliedto a single-tree block. For local dual-tree chroma block, the palettemode is disabled. Because the local dual-tree luma block may onlycontain luma component, the value of luma component is signaled and adefault value can be set to the chroma component for the new paletteentry. As an example, the default value may be related to the bit depthof the video sequence. As another example, the default value may bezero.

Moreover, for non 4:4:4 color format, only luma values are signaled forpixels only containing luma components when they are coded using escapemode. FIG. 15 illustrates an exemplary Table 6 showing a part of thecoding unit syntax table, according to some embodiments of the presentdisclosure. FIG. 16 illustrates an exemplary Table 7 showing a part ofthe palette coding syntax table, according to some embodiments of thepresent disclosure. The palette coding syntax table can apply thepalette mode to a CU containing luma local dual trees. The syntaxchanges in Table 6 and Table 7 consistent with the present embodimentsare italicized in box 1501 and boxes 1601-1602, respectively.

In some embodiments of the present disclosure, with disabling thepalette for chroma local dual tree, the palette design is simplified.

FIG. 17 illustrates an exemplary palette coding semantics and decodingprocess for palette mode, according to some embodiments of the presentdisclosure. As shown in FIG. 17 , the proposed syntax changes to thesection 7.4.12.6 and the section 8.4.5.3 in VVC draft 7 are italicizedin boxes 1701-1705. For the local dual-tree blocks, when performing thepalette predictor update, a default value is first filled in the currentpalette. Then, all three components are involved in the process ofpalette predictor update. It is a requirement of bitstream conformancethat the value of PredictorPaletteSize[startComp] is in the range of 0to 63, inclusive.

FIG. 18 illustrates a flowchart of an exemplary video processing method1800, according to some embodiments of the present disclosure. In someembodiments, method 1800 can be performed by a decoder (e.g., decoder300 of FIG. 3 ) or one or more software or hardware components of anapparatus (e.g., apparatus 400 of FIG. 4 ). For example, a processor(e.g., processor 402 of FIG. 4 ) can perform method 1800. In someembodiments, method 1800 can be implemented by a computer programproduct, embodied in a computer-readable medium, includingcomputer-executable instructions, such as program code, executed bycomputers (e.g., apparatus 400 of FIG. 4 ).

At step 1801, a palette entry for palette coding a target CU can bereceived. For example, a decoder (e.g., decoder 300 of FIG. 3 ) canreceive a bitstream including one or more palette entries (e.g.,new_palette_entries[cIdx][i] in Table 3 of FIG. 9 ) for palette coding atarget CU.

At step 1803, a determination can be made on whether the target CU iscoded with separate luma and chroma trees. For example, thedetermination can be made on whether a condition (treeType!=SINGLE_TREE) is satisfied. If treeType !=SINGLE_TREE, the target CUcan be determined to be coded with separate luma and chroma trees.

At step 1805, a determination can be made on whether the target CU ispart of a single-tree slice. In some embodiments, method 1800 caninclude determining whether the target CU is part of a P slice or a Bslice (e.g., slice_type !=I) or determining whether the target CU ispart of a single tree I slice (e.g., qtbtt_dual_tree_intra_flag==0).

At step 1807, in response to the target CU being determined to be (a)coded with separate luma and chroma trees and (b) part of a single-treeslice, a first component of the target CU can be decoded based on thereceived palette entry, and a second component of the target CU can bedecoded based on a default palette entry. In some embodiments, method1800 can include: in response to the target CU being determined to bepart of a P slice or a B slice or be part of a single tree I slice,decoding the first and second components of the target CU based on thereceived palette entry. The first component is luma component and thesecond component is chroma component, or the first component is chromacomponent and the second component is luma component.

In some embodiments, method 1800 can include receiving a reuse flag forreusing a palette entry to palette code the target CU and updating apalette predictor of the target CU based on the received palette entryand the received reuse flag. In some embodiments, a size of the palettepredictor of the target CU is in a range of 0 to 63, inclusive. In someembodiments, method 1800 can include updating a palette predictor of thetarget CU based on the received palette entry. In some embodiments, thepalette predictor of the target CU is not updated after the firstcomponent and the second component are decoded.

FIG. 19 illustrates a flowchart of an exemplary video processing method1900, according to some embodiments of the present disclosure. In someembodiments, method 1900 can be performed by an encoder (e.g., encoder200 of FIG. 2 ), a decoder (e.g., decoder 300 of FIG. 3 ) or one or moresoftware or hardware components of an apparatus (e.g., apparatus 400 ofFIG. 4 ). For example, a processor (e.g., processor 402 of FIG. 4 ) canperform method 1900. In some embodiments, method 1900 can be implementedby a computer program product, embodied in a computer-readable medium,including computer-executable instructions, such as program code,executed by computers (e.g., apparatus 400 of FIG. 4 ).

At step 1901, method 1900 can include signaling a flag indicating that apalette mode is enabled for a target CU. The flag can be signaledregardless of whether a chroma sampling format is used for the targetCU. In some embodiments, the flag is signaled in a SPS. The chromasampling format can include one or more of 4:4:4 format, 4:2:2 format,or 4:2:0 format.

At step 1903, method 1900 can also include determining the chromasampling format used for the target CU (e.g., 4:4:4 format, 4:2:2format, or 4:2:0 format). In some embodiments, method 1900 can include:based on the determined chroma sampling format (e.g., 4:4:4 format),signaling corresponding syntax elements (e.g., syntax elementsps_act_enabled_flag in Table 1 of FIG. 7 ).

FIG. 20 illustrates a flowchart of an exemplary video processing method2000, according to some embodiments of the present disclosure. In someembodiments, method 2000 can be performed by an encoder (e.g., encoder200 of FIG. 2 ), a decoder (e.g., decoder 300 of FIG. 3 ) or one or moresoftware or hardware components of an apparatus (e.g., apparatus 400 ofFIG. 4 ). For example, a processor (e.g., processor 402 of FIG. 4 ) canperform method 2000. In some embodiments, method 2000 can be implementedby a computer program product, embodied in a computer-readable medium,including computer-executable instructions, such as program code,executed by computers (e.g., apparatus 400 of FIG. 4 ).

At step 2001, a determination can be made on whether the target CU iscoded with separate luma and chroma trees. For example, thedetermination can be made on whether a condition (treeType!=SINGLE_TREE) is satisfied. If treeType !=SINGLE_TREE, the target CUcan be determined to be coded with separate luma and chroma trees.

At step 2003, a determination can be made on whether the target CU ispart of a single-tree slice. In some embodiments, method 2000 caninclude determining whether the target CU is part of a P slice or a Bslice (e.g., slice_type !=I) or determining whether the target CU ispart of a single tree I slice (e.g., qtbtt_dual_tree_intra_flag==0).

At step 2005, in response to the target CU being determined to be (a)coded with separate luma and chroma trees and (b) part of a single-treeslice, palette mode can be determined to be disallowed for the target CU(e.g., Table 2 of FIG. 8 ).

FIG. 21 illustrates a flowchart of an exemplary video processing method2100, according to some embodiments of the present disclosure. In someembodiments, method 2100 can be performed by an encoder (e.g., encoder200 of FIG. 2 ), a decoder (e.g., decoder 300 of FIG. 3 ) or one or moresoftware or hardware components of an apparatus (e.g., apparatus 400 ofFIG. 4 ). For example, a processor (e.g., processor 402 of FIG. 4 ) canperform method 2100. In some embodiments, method 2100 can be implementedby a computer program product, embodied in a computer-readable medium,including computer-executable instructions, such as program code,executed by computers (e.g., apparatus 400 of FIG. 4 ).

At step 2101, a determination can be made on whether the target CU iscoded with separate luma and chroma trees. For example, thedetermination can be made on whether a condition (treeType!=SINGLE_TREE) is satisfied. If treeType !=SINGLE_TREE, the target CUcan be determined to be coded with separate luma and chroma trees.

At step 2103, a determination can be made on whether the target CU ispart of a single-tree slice. In some embodiments, method 2100 caninclude determining whether the target CU is part of a P slice or a Bslice (e.g., slice_type !=I) or determining whether the target CU ispart of a single tree I slice (e.g., qtbtt_dual_tree_intra_flag==0).

At step 2105, in response to the target CU being determined to be (a)coded with separate luma and chroma trees and (b) part of a single-treeslice, a reuse flag for reusing a palette entry to palette code thetarget CU can be signaled. No new palette entry is signaled for palettecoding the target CU (e.g., Table 3 of FIG. 9 ).

In some embodiments, method 2100 can include: in response to the targetCU being determined to be not (a) coded with separate luma and chromatrees or (b) part of a single-tree slice, signaling a palette entry forpalette coding the target CU (e.g., Table 3 of FIG. 9 ).

In some embodiments, method 2100 can include: determining whether apixel in the target CU only contains luma component, and in response tothe pixel being determined to only contain luma component, onlysignaling luma palette escape value for the pixel if the pixel is codedusing escape mode CU (e.g., Table 3 of FIG. 9 ).

FIG. 22 illustrates a flowchart of an exemplary video processing method2200, according to some embodiments of the present disclosure. In someembodiments, method 2200 can be performed by an encoder (e.g., encoder200 of FIG. 2 ), a decoder (e.g., decoder 300 of FIG. 3 ) or one or moresoftware or hardware components of an apparatus (e.g., apparatus 400 ofFIG. 4 ). For example, a processor (e.g., processor 402 of FIG. 4 ) canperform method 2200. In some embodiments, method 2200 can be implementedby a computer program product, embodied in a computer-readable medium,including computer-executable instructions, such as program code,executed by computers (e.g., apparatus 400 of FIG. 4 ).

At step 2201, a determination can be made on whether a pixel in a targetcoding unit (CU) only contains luma component. At step 2203, in responseto the pixel being determined to only contain luma component, only lumapalette escape value for the pixel can be signaled if the pixel is codedusing escape mode (e.g., Table 4 of FIG. 11 ).

FIG. 23 illustrates a flowchart of an exemplary video processing method2300, according to some embodiments of the present disclosure. In someembodiments, method 2300 can be performed by a decoder (e.g., decoder300 of FIG. 3 ) or one or more software or hardware components of anapparatus (e.g., apparatus 400 of FIG. 4 ). For example, a processor(e.g., processor 402 of FIG. 4 ) can perform method 2300. In someembodiments, method 2300 can be implemented by a computer programproduct, embodied in a computer-readable medium, includingcomputer-executable instructions, such as program code, executed bycomputers (e.g., apparatus 400 of FIG. 4 ).

At step 2301, a bitstream can be received. The bitstream can include areuse flag for reusing a palette entry to palette code a target CU. Forexample, a decoder (e.g., decoder 300 of FIG. 3 ) can receive abitstream including one or more reuse flags (e.g., palette_predictor_runin Table 3 of FIG. 9 ) for reusing a palette entry to palette code atarget CU.

At step 2303, a determination can be made on whether the target CU iscoded with separate luma and chroma trees. For example, thedetermination can be made on whether a condition (treeType!=SINGLE_TREE) is satisfied. If treeType !=SINGLE_TREE, the target CUcan be determined to be coded with separate luma and chroma trees.

At step 2305, a determination can be made on whether the target CU ispart of a single-tree slice. In some embodiments, method 2300 caninclude determining whether the target CU is part of a P slice or a Bslice (e.g., slice_type !=I) or determining whether the target CU ispart of a single tree I slice (e.g., qtbtt_dual_tree_intra_flag==0).

At step 2307, in response to the target CU being determined to be (a)coded with separate luma and chroma trees and (b) part of a single-treeslice, a luma component and a chroma component of the target CU can bedecoded based on the received reuse flag. The received bitstream doesnot include palette entry for palette coding the target CU. In someembodiments, method 2300 can include: in response to the target CU beingdetermined to be part of a P slice or a B slice or be part of a singletree I slice, decoding the luma component and the chroma component ofthe target CU based on the received reuse flag and a palette entry forpalette coding the target CU in the bitstream.

In some embodiments, method 2300 can include updating a palettepredictor of the target CU based on the received reuse flag. Method 230can also include: in response to the target CU being determined to bepart of a P slice or a B slice or be part of a single tree I slice,updating a palette predictor of the target CU based on the receivedreuse flag and a palette entry for palette coding the target CU in thebitstream. In some embodiments, a size of the palette predictor of thetarget CU is in a range of 0 to 63, inclusive.

In some embodiments, a non-transitory computer-readable storage mediumincluding instructions is also provided, and the instructions may beexecuted by a device (such as the disclosed encoder and decoder), forperforming the above-described methods. Common forms of non-transitorymedia include, for example, a floppy disk, a flexible disk, hard disk,solid state drive, magnetic tape, or any other magnetic data storagemedium, a CD-ROM, any other optical data storage medium, any physicalmedium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROMor any other flash memory, NVRAM, a cache, a register, any other memorychip or cartridge, and networked versions of the same. The device mayinclude one or more processors (CPUs), an input/output interface, anetwork interface, and/or a memory.

The embodiments may further be described using the following clauses:

1. A video processing method, comprising:

receiving a first palette entry for palette coding a target coding unit(CU);

determining whether the target CU is part of a single-tree slice;

determining whether the target CU is coded with separate luma and chromatrees; and

in response to the target CU being determined to be part of asingle-tree slice and be coded with separate luma and chroma trees,

-   -   decoding a first component of the target CU based on the first        palette entry, and    -   decoding a second component of the target CU based on a default        palette entry.        2. The method of clause 1, wherein receiving the first palette        entry for palette coding the target CU comprises:

receiving a flag associated with a second palette entry; and

including the second palette entry in a palette predictor of the targetCU based on the received flag.

3. The method of clause 2, wherein a size of the palette predictor ofthe target CU is in a range of 0 to 63, inclusive.4. The method of any one of clauses 1-3, wherein receiving the firstpalette entry for palette coding the target CU comprises:

updating a palette predictor of the target CU based on the first paletteentry.

5. The method of any one of clauses 1-4, wherein determining whether thetarget CU is part of a single-tree slice comprises:

determining whether the target CU is part of a P slice or a B slice; or

determining whether the target CU is part of a single tree I slice.

6. The method of clause 5, further comprising:

in response to the target CU being determined to be part of a P slice ora B slice or be part of a single tree I slice, decoding the first andsecond components of the target CU based on the first palette entry.

7. The method of any one of clauses 1-6, wherein:

the first component is a luma component and the second component is achroma component; or

the first component is a chroma component and the second component is aluma component.

8. The method of clause 1, wherein a palette predictor of the target CUis not updated after the first component and the second component aredecoded.9. A video processing apparatus, comprising:

at least one memory for storing instructions; and

at least one processor configured to execute the instructions to causethe apparatus to perform:

-   -   receiving a first palette entry for palette coding a target        coding unit (CU);    -   determining whether the target CU is part of a single-tree        slice;    -   determining whether the target CU is coded with separate luma        and chroma trees; and    -   in response to the target CU being determined to be part of a        single-tree slice and be coded with separate luma and chroma        trees,        -   decoding a first component of the target CU based on the            first palette entry, and        -   decoding a second component of the target CU based on a            default palette entry.            10. The apparatus of clause 9, wherein the at least one            processor is configured to execute the instructions to cause            the apparatus to perform:

receiving a flag associated with a second palette entry; and

including the second palette entry in a palette predictor of the targetCU based on the received flag.

11. The apparatus of clause 10, wherein a size of the palette predictorof the target CU is in a range of 0 to 63, inclusive.12. The apparatus of any one of clauses 9-11, wherein the at least oneprocessor is configured to execute the instructions to cause theapparatus to perform:

updating a palette predictor of the target CU based on the first paletteentry.

13. The apparatus of any one of clauses 9-12, wherein the at least oneprocessor is configured to execute the instructions to cause theapparatus to perform:

determining whether the target CU is part of a P slice or a B slice; or

determining whether the target CU is part of a single tree I slice.

14. The apparatus of clause 13, wherein the at least one processor isconfigured to execute the instructions to cause the apparatus toperform:

in response to the target CU being determined to be part of a P slice ora B slice or be part of a single tree I slice, decoding the first andsecond components of the target CU based on the first palette entry.

15. The apparatus of any one of clauses 9-14, wherein

the first component is a luma component and the second component is achroma component; or

the first component is a chroma component and the second component is aluma component.

16. The apparatus of clause 9, wherein a palette predictor of the targetCU is not updated after the first component and the second component aredecoded.17. A non-transitory computer readable storage medium storing a set ofinstructions that are executable by one or more processing devices tocause a video processing apparatus to perform:

receiving a first palette entry for palette coding a target coding unit(CU);

determining whether the target CU is part of a single-tree slice;

determining whether the target CU is coded with separate luma and chromatrees; and

in response to the target CU being determined to be part of asingle-tree slice and be coded with separate luma and chroma trees,

-   -   decoding a first component of the target CU based on the first        palette entry, and    -   decoding a second component of the target CU based on a default        palette entry.        18. The non-transitory computer readable storage medium of        clause 17, wherein the set of instructions are executable by the        one or more processing devices to cause the video processing        apparatus to perform:

receiving a flag associated with a second palette entry; and

including the second palette entry in a palette predictor of the targetCU based on the received flag.

19. The non-transitory computer readable storage medium of clause 18,wherein a size of the palette predictor of the target CU is in a rangeof 0 to 63, inclusive.20. The non-transitory computer readable storage medium of any one ofclause 17-19, wherein the set of instructions are executable by the oneor more processing devices to cause the video processing apparatus toperform:

updating a palette predictor of the target CU based on the first paletteentry.

21. The non-transitory computer readable storage medium of any one ofclauses 17-20, wherein the set of instructions are executable by the oneor more processing devices to cause the video processing apparatus toperform:

determining whether the target CU is part of a P slice or a B slice; or

determining whether the target CU is part of a single tree I slice.

22. The non-transitory computer readable storage medium of clause 21,wherein the set of instructions are executable by the one or moreprocessing devices to cause the video processing apparatus to perform:

in response to the target CU being determined to be part of a P slice ora B slice or be part of a single tree I slice, decoding the first andsecond components of the target CU based on the first palette entry.

23. The non-transitory computer readable storage medium of any one ofclauses 17-22, wherein

the first component is a luma component and the second component is achroma component; or

the first component is a chroma component and the second component is aluma component.

24. The non-transitory computer readable storage medium of clause 17,wherein a palette predictor of the target CU is not updated after thefirst component and the second component are decoded.25. A video processing method, comprising:

signaling a flag indicating that a palette mode is enabled for a targetcoding unit (CU),

wherein the flag is signaled regardless of whether a chroma samplingformat is used for the target CU.

26. The method of clause 25, wherein the flag is signaled in a sequenceparameter set (SPS).27. The method of any one of clauses 25 and 26, wherein the chromasampling format comprises one or more of:

4:4:4 format,

4:2:2 format, or

4:2:0 format.

28. A video processing method, comprising:

determining whether the target CU is part of a single-tree slice;

determining whether a target coding unit (CU) is coded with separateluma and chroma trees; and

in response to the target CU being determined to be part of asingle-tree slice and be coded with separate luma and chroma trees,determining that palette mode is disallowed for the target CU.

29. The method of clause 28, wherein determining whether the target CUis part of a single-tree slice comprises:

determining whether the target CU is part of a P slice or a B slice; or

determining whether the target CU is part of a single tree I slice.

30. The method of clause 29, further comprising:

in response to the target CU being determined to be part of a P slice ora B slice or be part of a single tree I slice, determining that palettemode is allowed for the target CU.

31. A video processing method, comprising:

determining whether the target CU is part of a single-tree slice;

determining whether a target coding unit (CU) is coded with separateluma and chroma trees; and

in response to the target CU being determined to be part of asingle-tree slice and be coded with separate luma and chroma trees,signaling a reuse flag for reusing a palette entry to palette code thetarget CU, wherein no new palette entry is signaled for palette codingthe target CU.

32. The method of clause 31, wherein determining whether the target CUis part of a single-tree slice comprises:

determining whether the target CU is part of a P slice or a B slice; or

determining whether the target CU is part of a single tree I slice.

33. The method of any one of clauses 31 and 32, further comprising:

in response to that the target CU is not part of a single-tree slice oris not coded with separate luma and chroma trees, signaling a paletteentry for palette coding the target CU.

34. The method of any one of clauses 31-33, further comprising:

determining whether a pixel in the target CU contains chroma component,the pixel being coded using escape mode; and

in response to that the pixel does not contain chroma component,signaling a luma palette escape value for the pixel, wherein no chromapalette escape value for the pixel is signaled.

35. A video processing method, comprising:

determining whether a pixel in a target coding unit (CU) contain chromacomponent, the pixel being coded using escape mode; and

in response to that the pixel does not contain chroma component,signaling a luma palette escape value, wherein no chroma palette escapevalue for the pixel is signaled.

36. A video processing method, comprising:

receiving a bitstream comprising a reuse flag for reusing a paletteentry to palette code a target coding unit (CU);

determining whether the target CU is part of a single-tree slice;

determining whether the target CU is coded with separate luma and chromatrees; and

in response to the target CU being determined to be part of asingle-tree slice and be coded with separate luma and chroma trees,decoding a luma component and a chroma component of the target CU basedon the received reuse flag, the bitstream comprising no palette entryfor palette coding the target CU that is part of a single-tree slice andis coded with separate luma and chroma trees.

37. The method of clause 36, further comprising:

updating a palette predictor of the target CU based on the receivedreuse flag.

38. The method of any one of clauses 36 and 37, wherein determiningwhether the target CU is part of a single-tree slice comprises:

determining whether the target CU is part of a P slice or a B slice; or

determining whether the target CU is part of a single tree I slice.

39. The method of clause 38, further comprising:

in response to the target CU being determined to be part of a P slice ora B slice or be part of a single tree I slice, decoding the lumacomponent and the chroma component of the target CU based on thereceived reuse flag and a palette entry for palette coding the target CUin the bitstream.

40. The method of any one of clauses 38 and 39, further comprising:

in response to the target CU being determined to be part of a P slice ora B slice or be part of a single tree I slice, updating a palettepredictor of the target CU based on the received reuse flag and apalette entry for palette coding the target CU in the bitstream.

41. The method of any one of clauses 37 and 40, wherein a size of thepalette predictor of the target CU is in a range of 0 to 63, inclusive.42. A video processing apparatus, comprising:

at least one memory for storing instructions; and

at least one processor configured to execute the instructions to causethe apparatus to perform:

-   -   signaling a flag indicating that a palette mode is enabled for a        target coding unit (CU),    -   wherein the flag is signaled regardless of whether a chroma        sampling format is used for the target CU.        43. The apparatus of clause 42, wherein the flag is signaled in        a sequence parameter set (SPS).        44. The apparatus of any one of clauses 42 and 43, wherein the        chroma sampling format comprises one or more of:

4:4:4 format,

4:2:2 format, or

4:2:0 format.

45. A video processing apparatus, comprising:

at least one memory for storing instructions; and

at least one processor configured to execute the instructions to causethe apparatus to perform:

-   -   determining whether the target CU is part of a single-tree        slice;    -   determining whether a target coding unit (CU) is coded with        separate luma and chroma trees; and    -   in response to the target CU being determined to be part of a        single-tree slice and be coded with separate luma and chroma        trees, determining that palette mode is disallowed for the        target CU.        46. The apparatus of clause 45, wherein the at least one        processor is configured to execute the instructions to cause the        apparatus to perform:

determining whether the target CU is part of a P slice or a B slice; or

determining whether the target CU is part of a single tree I slice.

47. The apparatus of clause 46, wherein the at least one processor isconfigured to execute the instructions to cause the apparatus toperform:

in response to the target CU being determined to be part of a P slice ora B slice or be part of a single tree I slice, determining that palettemode is allowed for the target CU.

48. A video processing apparatus, comprising:

at least one memory for storing instructions; and

at least one processor configured to execute the instructions to causethe apparatus to perform:

-   -   determining whether the target CU is part of a single-tree        slice;    -   determining whether a target coding unit (CU) is coded with        separate luma and chroma trees; and    -   in response to the target CU being determined to be part of a        single-tree slice and be coded with separate luma and chroma        trees, signaling a reuse flag for reusing a palette entry to        palette code the target CU, wherein no new palette entry is        signaled for palette coding the target CU.        49. The apparatus of clause 48, wherein the at least one        processor is configured to execute the instructions to cause the        apparatus to perform:

determining whether the target CU is part of a P slice or a B slice; or

determining whether the target CU is part of a single tree I slice.

50. The apparatus of any one of clauses 48 and 49, wherein the at leastone processor is configured to execute the instructions to cause theapparatus to perform:

in response to that the target CU is not part of a single-tree slice oris not coded with separate luma and chroma trees, signaling a paletteentry for palette coding the target CU.

51. The apparatus of any one of clauses 48-50, wherein the at least oneprocessor is configured to execute the instructions to cause theapparatus to perform:

determining whether a pixel in the target CU contains chroma component,the pixel being coded using escape mode; and

in response to that the pixel does not contain chroma component,signaling a luma palette escape value for the pixel, wherein no chromapalette escape value for the pixel is signaled.

52. A video processing apparatus, comprising:

at least one memory for storing instructions; and

at least one processor configured to execute the instructions to causethe apparatus to perform:

-   -   determining whether a pixel in a target coding unit (CU) contain        chroma component, the pixel being coded using escape mode; and    -   in response to that the pixel does not contain chroma component,        signaling a luma palette escape value, wherein no chroma palette        escape value for the pixel is signaled.        53. A video processing apparatus, comprising:

at least one memory for storing instructions; and

at least one processor configured to execute the instructions to causethe apparatus to perform:

-   -   receiving a bitstream comprising a reuse flag for reusing a        palette entry to palette code a target coding unit (CU);    -   determining whether the target CU is part of a single-tree        slice;    -   determining whether the target CU is coded with separate luma        and chroma trees; and    -   in response to the target CU being determined to be part of a        single-tree slice and be coded with separate luma and chroma        trees, decoding a luma component and a chroma component of the        target CU based on the received reuse flag, the bitstream        comprising no palette entry for palette coding the target CU        that is part of a single-tree slice and is coded with separate        luma and chroma trees.        54. The apparatus of clause 53, wherein the at least one        processor is configured to execute the instructions to cause the        apparatus to perform:

updating a palette predictor of the target CU based on the receivedreuse flag.

55. The apparatus of any one of clauses 53 and 54, wherein the at leastone processor is configured to execute the instructions to cause theapparatus to perform:

determining whether the target CU is part of a P slice or a B slice; or

determining whether the target CU is part of a single tree I slice.

56. The apparatus of clause 55, wherein the at least one processor isconfigured to execute the instructions to cause the apparatus toperform:

in response to the target CU being determined to be part of a P slice ora B slice or be part of a single tree I slice, decoding the lumacomponent and the chroma component of the target CU based on thereceived reuse flag and a palette entry for palette coding the target CUin the bitstream.

57. The apparatus of any one of clauses 55 and 56, wherein the at leastone processor is configured to execute the instructions to cause theapparatus to perform:

in response to the target CU being determined to be part of a P slice ora B slice or be part of a single tree I slice, updating a palettepredictor of the target CU based on the received reuse flag and apalette entry for palette coding the target CU in the bitstream.

58. The apparatus of any one of clauses 54 and 57, wherein a size of thepalette predictor of the target CU is in a range of 0 to 63, inclusive.59. A non-transitory computer readable storage medium storing a set ofinstructions that are executable by one or more processing devices tocause a video processing apparatus to perform:

signaling a flag indicating that a palette mode is enabled for a targetcoding unit (CU),

wherein the flag is signaled regardless of whether a chroma samplingformat is used for the target CU.

60. The non-transitory computer readable storage medium of clause 59,wherein the flag is signaled in a sequence parameter set (SPS).61. The non-transitory computer readable storage medium of any one ofclauses 59 and 60, wherein the chroma sampling format comprises one ormore of:

4:4:4 format,

4:2:2 format, or

4:2:0 format.

62. A non-transitory computer readable storage medium storing a set ofinstructions that are executable by one or more processing devices tocause a video processing apparatus to perform:

determining whether the target CU is part of a single-tree slice;

determining whether a target coding unit (CU) is coded with separateluma and chroma trees; and

in response to the target CU being determined to be part of asingle-tree slice and be coded with separate luma and chroma trees,determining that palette mode is disallowed for the target CU.

63. The non-transitory computer readable storage medium of clause 62,wherein the set of instructions are executable by the one or moreprocessing devices to cause the video processing apparatus to perform:

determining whether the target CU is part of a P slice or a B slice; or

determining whether the target CU is part of a single tree I slice.

64. The non-transitory computer readable storage medium of clause 63,wherein the set of instructions are executable by the one or moreprocessing devices to cause the video processing apparatus to perform:

in response to the target CU being determined to be part of a P slice ora B slice or be part of a single tree I slice, determining that palettemode is allowed for the target CU.

65. A non-transitory computer readable storage medium storing a set ofinstructions that are executable by one or more processing devices tocause a video processing apparatus to perform:

determining whether the target CU is part of a single-tree slice;

determining whether a target coding unit (CU) is coded with separateluma and chroma trees; and

in response to the target CU being determined to be part of asingle-tree slice and be coded with separate luma and chroma trees,signaling a reuse flag for reusing a palette entry to palette code thetarget CU, wherein no new palette entry is signaled for palette codingthe target CU.

66. The non-transitory computer readable storage medium of clause 65,wherein the set of instructions are executable by the one or moreprocessing devices to cause the video processing apparatus to perform:

determining whether the target CU is part of a P slice or a B slice; or

determining whether the target CU is part of a single tree I slice.

67. The non-transitory computer readable storage medium of any one ofclauses 65 and 66, wherein the set of instructions are executable by theone or more processing devices to cause the video processing apparatusto perform:

in response to that the target CU is not part of a single-tree slice oris not coded with separate luma and chroma trees, signaling a paletteentry for palette coding the target CU.

68. The non-transitory computer readable storage medium of any one ofclauses 65-67, wherein the set of instructions are executable by the oneor more processing devices to cause the video processing apparatus toperform:

determining whether a pixel in the target CU contains chroma component,the pixel being coded using escape mode; and

in response to that the pixel does not contain chroma component,signaling a luma palette escape value for the pixel, wherein no chromapalette escape value for the pixel is signaled.

69. A non-transitory computer readable storage medium storing a set ofinstructions that are executable by one or more processing devices tocause a video processing apparatus to perform:

determining whether a pixel in a target coding unit (CU) contain chromacomponent, the pixel being coded using escape mode; and

in response to that the pixel does not contain chroma component,signaling a luma palette escape value, wherein no chroma palette escapevalue for the pixel is signaled.

70. A non-transitory computer readable storage medium storing a set ofinstructions that are executable by one or more processing devices tocause a video processing apparatus to perform:

receiving a bitstream comprising a reuse flag for reusing a paletteentry to palette code a target coding unit (CU);

determining whether the target CU is part of a single-tree slice;

determining whether the target CU is coded with separate luma and chromatrees; and

in response to the target CU being determined to be part of asingle-tree slice and be coded with separate luma and chroma trees,decoding a luma component and a chroma component of the target CU basedon the received reuse flag, the bitstream comprising no palette entryfor palette coding the target CU that is part of a single-tree slice andis coded with separate luma and chroma trees.

71. The non-transitory computer readable storage medium of clause 70,wherein the set of instructions are executable by the one or moreprocessing devices to cause the video processing apparatus to perform:

updating a palette predictor of the target CU based on the receivedreuse flag.

72. The non-transitory computer readable storage medium of any one ofclauses 70 and 71, wherein the set of instructions are executable by theone or more processing devices to cause the video processing apparatusto perform:

determining whether the target CU is part of a P slice or a B slice; or

determining whether the target CU is part of a single tree I slice.

73. The non-transitory computer readable storage medium of clause 72,wherein the set of instructions are executable by the one or moreprocessing devices to cause the video processing apparatus to perform:

in response to the target CU being determined to be part of a P slice ora B slice or be part of a single tree I slice, decoding the lumacomponent and the chroma component of the target CU based on thereceived reuse flag and a palette entry for palette coding the target CUin the bitstream.

74. The non-transitory computer readable storage medium of any one ofclauses 72 and 73, wherein the set of instructions are executable by theone or more processing devices to cause the video processing apparatusto perform:

in response to the target CU being determined to be part of a P slice ora B slice or be part of a single tree I slice, updating a palettepredictor of the target CU based on the received reuse flag and apalette entry for palette coding the target CU in the bitstream.

75. The non-transitory computer readable storage medium of any one ofclauses 72 and 74, wherein a size of the palette predictor of the targetCU is in a range of 0 to 63, inclusive.

It should be noted that, the relational terms herein such as “first” and“second” are used only to differentiate an entity or operation fromanother entity or operation, and do not require or imply any actualrelationship or sequence between these entities or operations. Moreover,the words “comprising,” “having,” “containing,” and “including,” andother similar forms are intended to be equivalent in meaning and be openended in that an item or items following any one of these words is notmeant to be an exhaustive listing of such item or items, or meant to belimited to only the listed item or items.

As used herein, unless specifically stated otherwise, the term “or”encompasses all possible combinations, except where infeasible. Forexample, if it is stated that a database may include A or B, then,unless specifically stated otherwise or infeasible, the database mayinclude A, or B, or A and B. As a second example, if it is stated that adatabase may include A, B, or C, then, unless specifically statedotherwise or infeasible, the database may include A, or B, or C, or Aand B, or A and C, or B and C, or A and B and C.

It is appreciated that the above described embodiments can beimplemented by hardware, or software (program codes), or a combinationof hardware and software. If implemented by software, it may be storedin the above-described computer-readable media. The software, whenexecuted by the processor can perform the disclosed methods. Thecomputing units and other functional units described in this disclosurecan be implemented by hardware, or software, or a combination ofhardware and software. One of ordinary skill in the art will alsounderstand that multiple ones of the above described modules/units maybe combined as one module/unit, and each of the above describedmodules/units may be further divided into a plurality ofsub-modules/sub-units.

In the foregoing specification, embodiments have been described withreference to numerous specific details that can vary from implementationto implementation. Certain adaptations and modifications of thedescribed embodiments can be made. Other embodiments can be apparent tothose skilled in the art from consideration of the specification andpractice of the invention disclosed herein. It is intended that thespecification and examples be considered as exemplary only, with a truescope and spirit of the invention being indicated by the followingclaims. It is also intended that the sequence of steps shown in figuresare only for illustrative purposes and are not intended to be limited toany particular sequence of steps. As such, those skilled in the art canappreciate that these steps can be performed in a different order whileimplementing the same method.

In the drawings and specification, there have been disclosed exemplaryembodiments. However, many variations and modifications can be made tothese embodiments. Accordingly, although specific terms are employed,they are used in a generic and descriptive sense only and not forpurposes of limitation.

What is claimed is:
 1. A video processing method, comprising: signaling a flag indicating that a palette mode is enabled for a target coding unit (CU), wherein the flag is signaled regardless of whether a chroma sampling format is used for the target CU.
 2. The method of claim 1, wherein the flag is signaled in a sequence parameter set (SPS).
 3. The method of claim 1, wherein the chroma sampling format comprises one or more of: a 4:4:4 format, a 4:2:2 format, or a 4:2:0 format.
 4. A video processing method, comprising: signaling a flag indicating that a palette mode is enabled for a target coding unit (CU), wherein the flag is signaled regardless of whether a chroma sampling format is used for the target CU; and encoding the target CU using the palette mode.
 5. The method of claim 4, wherein the flag is signaled in a sequence parameter set (SPS).
 6. The method of claim 4, wherein the chroma sampling format comprises one or more of: a 4:4:4 format, a 4:2:2 format, or a 4:2:0 format.
 7. A non-transitory computer readable medium storing a bitstream, wherein the bitstream comprises: a flag indicating that a palette mode is enabled for a target coding unit (CU), wherein the flag is present regardless of whether a chroma sampling format is used for the target CU.
 8. The non-transitory computer readable storage medium of claim 7, wherein the flag is signaled in a sequence parameter set (SPS).
 9. The non-transitory computer readable storage medium of claim 7, wherein the chroma sampling format comprises one or more of: a 4:4:4 format, a 4:2:2 format, or a 4:2:0 format. 